1. Field of the Invention
The present invention relates to image processors and processing methods thereof for treating blurs in taken images produced by camera shakes or the like, and particularly to reduction in image-processing time required to compensate the blurs.
2. Description of the Related Art
A great number of digital and movie cameras equipped with an image sensor, such as a CCD (Charge Coupled Device) sensor and a CMOS (Complementary Metal Oxide Semiconductor) sensor, have recently been marketed, and even beginners have been able to readily take still pictures or moving pictures; however, when a general user takes a picture, blurs are inevitably produced in the picture unless a camera is fixed with a tripod or the like; in consequent, various methods have been devised in order to compensate the blurs.
The methods are roughly categorized into two groups. One of the methods is to mechanically control the orientations of lenses and prisms by detecting with an acceleration sensor or the like movement of a camera itself, and the other is to compensate image blurs by applying image processing to the digital data of a taken picture and calculating blurring amounts.
Despite its high accuracy of compensating blurs, the former requires an acceleration sensor and parts for lens control; therefore, there are problems in terms of downsizing and cost reduction of the device. In contrast, despite its disadvantage of deterioration in resolution, the latter can, merely by means of signal processing, provide the compensation for camera shakes, and can be implemented with low cost; therefore, the latter method has been widely utilized.
Japanese Laid-Open Patent Publication 1993-75913 discloses a motion-vector detecting and camera-shake compensating circuits that are examples of conventional arts with regard to the camera-shake compensation utilizing the image processing. In the foregoing Japanese Laid-Open Patent Publication, an input image is divided into a plurality of areas, and motion vectors in selected areas among the plurality of regions are calculated. If the number of the selected areas is increased in order to raise the accuracy of the motion vectors, the calculating amount of the motion vectors increases; therefore, a circuit for determining the reliability of correlativity calculation is provided for each area, and the motion-vector calculation is limited to the areas that are determined by the determining circuit to be reliable; however, when all the areas are reliable, the motion-vector calculation is also carried out in all the areas; thus, processing speed has been an issue to be solved.